Perhaps I'm overlooking a plugin that does this, it seems so logical it must exist =).
A plugin that gives me ONE link (text or image) to ONE random post of the past. A 'jumper'. A link from which the visitor can keep jumping at random from one post to the other. I've seen it before and it's fun to use, especially when being new to a site.
If it doesn't exist would someone be willing to create it? I'm not into PHP, but it seems to be rather easy? Count the total number of posts, random('number') and the creation of the link?